18.1-18.5 Flashcards
(25 cards)
Hormone
Mediator that is released in one location of the body but regulates in another location.
Hormon-to excite or get moving
2 types of glands:
Endocrine and exocrine
Exocrine
Secrete into ducts that carry into body cavities, organs, and outside the body
Endocrine
Secrete hormones into interstitial fluid surrounding the secretory cells rather than into ducts.
What glands are part of the Endocrine Glands?
5 specific glands:
Pituitary, thyroid, parathyroid, adrenal, and pineal.
Organs that contain cells that excrete hormones (endocrine):
Hypothalamus, thymus, pancreas, ovaries, testes, kidney, stomach, liver, small intestine, skin, heart, adipose tissue, and placenta.
Endocrinology
Science of the structure and function, and diagnosis and treatment, of endocrine glands
Down-regulation
When the target-cell receptors decrease in number, if a hormone is present in excess.
(Makes a target cell less sensitive to a hormone)
Up-regulation
When a hormone is deficient, receptors increase, making a target cell more sensitive to a hormone.
Circulating hormones
Pass from the secretory cell into interstitial fluid and then the blood
Local hormones
Act locally on the same or nearby cell that secreted them without entering bloodstream.
Local hormones that act on neighboring cells
Paracrines
Local hormones that act upon the same cell that secreted them are called
Autocrines
Auto means self
2 chemical classes of hormones are
Lipid-soluble hormones
Water-soluble hormones
3 types of lipid soluble hormones:
(1) steroid hormones
(2) thyroid hormones
(3) nitric oxide
3 types of water-soluble hormones
(1) amine hormones-(modified amino acid component)
(2) peptide hormones and protein hormones
(3) eicosanoid hormones
2 types: PG’s and LT’s
Hormone transport in the blood. How does each transport:
Water soluble & lipid soluble.
Water soluble hormones travel in free form.
Lipid soluble hormones are bound to transport proteins.
3 functions of transport proteins that are synthesized by cells in the liver.
- Make lipid-soluble hormones temporarily water-soluble
- Slow the rate of hormone loss in urine
- Provide a reserve of hormones present in bloodstream
Free fraction
.1-10% of lipid soluble hormones aren’t bound to transport proteins. It diffuses out of capillaries, binds to receptors, and triggers responses.They are also easily replaced.
Action of lipid soluble hormone
1) free soluble hormone diffuses into cell
2) hormone binds to receptors and alters DNA genes
3) mRNA enters cytosol, and directs synthesis of new protein on ribosomes
4) new proteins carry out the response typical of that hormone
Action of water soluble hormone
1) water soluble hormone (1st messenger) diffuses through interstitial fluid and binds to receptor at plasma membrane
G PROTEIN IS ACTIVATED.-which activates ADENYLATE CYCLASE
2) AC converts ATP into cyclic AMP.
3) cyclic AMP (second messenger) activates protein kinases
4) activated protein kinases phosphorylate cellular proteins
5) phosphorylated proteins produce physiological responses.
6) phosphodiesterase inactivates cAMP.
The responsiveness of a target cell to a hormone depends on (3 things)
1) hormone concentration
2) abundance of hormone receptors
3) influences exerted by other hormones
Synergistic effect
When the effect of two hormones acting together is greater or more extensive than the effect of each alone
Antagonistic effect
When the hormone opposes the actions of another hormone
